From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Nicholas Piggin <npiggin@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Arnd Bergmann <arnd@arndb.de>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Helge Deller <deller@gmx.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
Kees Cook <keescook@chromium.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Paul Mackerras <paulus@samba.org>
Cc: linux-arch@vger.kernel.org, linux-ia64@vger.kernel.org,
linux-parisc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v3 07/12] asm-generic: Define 'func_desc_t' to commonly describe function descriptors
Date: Mon, 18 Oct 2021 09:07:21 +0200 [thread overview]
Message-ID: <802b3ff9-8ada-b45b-2b69-b6a23f0c3664@csgroup.eu> (raw)
In-Reply-To: <1634538449.eah9b31bbz.astroid@bobo.none>
Le 18/10/2021 à 08:29, Nicholas Piggin a écrit :
> Excerpts from Christophe Leroy's message of October 17, 2021 10:38 pm:
>> We have three architectures using function descriptors, each with its
>> own type and name.
>>
>> Add a common typedef that can be used in generic code.
>>
>> Also add a stub typedef for architecture without function descriptors,
>> to avoid a forest of #ifdefs.
>>
>> It replaces the similar 'func_desc_t' previously defined in
>> arch/powerpc/kernel/module_64.c
>>
>> Reviewed-by: Kees Cook <keescook@chromium.org>
>> Acked-by: Arnd Bergmann <arnd@arndb.de>
>> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
>> ---
>
> [...]
>
>> diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
>> index a918388d9bf6..33b51efe3a24 100644
>> --- a/include/asm-generic/sections.h
>> +++ b/include/asm-generic/sections.h
>> @@ -63,6 +63,9 @@ extern __visible const void __nosave_begin, __nosave_end;
>> #else
>> #define dereference_function_descriptor(p) ((void *)(p))
>> #define dereference_kernel_function_descriptor(p) ((void *)(p))
>> +typedef struct {
>> + unsigned long addr;
>> +} func_desc_t;
>> #endif
>>
>
> I think that deserves a comment. If it's just to allow ifdef to be
> avoided, I guess that's okay with a comment. Would be nice if you could
> cause it to generate a link time error if it was ever used like
> undefined functions, but I guess you can't. It's not a necessity though.
>
I tried to explain it in the commit message, but I can add a comment
here in addition for sure.
By the way, it IS used in powerpc's module_64.c:
static func_desc_t func_desc(unsigned long addr)
{
return (func_desc_t){addr};
}
static unsigned long func_addr(unsigned long addr)
{
return func_desc(addr).addr;
}
next prev parent reply other threads:[~2021-10-18 7:07 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-17 12:38 [PATCH v3 00/12] Fix LKDTM for PPC64/IA64/PARISC Christophe Leroy
2021-10-17 12:38 ` [PATCH v3 01/12] powerpc: Move and rename func_descr_t Christophe Leroy
2021-10-18 5:58 ` Nicholas Piggin
2022-02-11 0:51 ` Kees Cook
2021-10-17 12:38 ` [PATCH v3 02/12] powerpc: Use 'struct func_desc' instead of 'struct ppc64_opd_entry' Christophe Leroy
2021-10-17 12:38 ` [PATCH v3 03/12] powerpc: Remove " Christophe Leroy
2021-10-17 12:38 ` [PATCH v3 04/12] powerpc: Prepare func_desc_t for refactorisation Christophe Leroy
2021-10-18 6:27 ` Nicholas Piggin
2021-10-18 7:08 ` Christophe Leroy
2022-02-11 0:54 ` Kees Cook
2022-02-11 7:39 ` Segher Boessenkool
2022-02-14 10:30 ` Christophe Leroy
2021-10-17 12:38 ` [PATCH v3 05/12] ia64: Rename 'ip' to 'addr' in 'struct fdesc' Christophe Leroy
2021-10-17 12:38 ` [PATCH v3 06/12] asm-generic: Define CONFIG_HAVE_FUNCTION_DESCRIPTORS Christophe Leroy
2021-10-17 12:38 ` [PATCH v3 07/12] asm-generic: Define 'func_desc_t' to commonly describe function descriptors Christophe Leroy
2021-10-18 6:29 ` Nicholas Piggin
2021-10-18 7:07 ` Christophe Leroy [this message]
2021-10-18 9:16 ` Nicholas Piggin
2021-10-17 12:38 ` [PATCH v3 08/12] asm-generic: Refactor dereference_[kernel]_function_descriptor() Christophe Leroy
2022-02-10 10:30 ` Michael Ellerman
2022-02-11 0:56 ` Kees Cook
2022-02-14 10:32 ` Christophe Leroy
2021-10-17 12:38 ` [PATCH v3 09/12] lkdtm: Force do_nothing() out of line Christophe Leroy
2021-10-17 12:38 ` [PATCH v3 10/12] lkdtm: Really write into kernel text in WRITE_KERN Christophe Leroy
2021-10-17 12:38 ` [PATCH v3 11/12] lkdtm: Fix execute_[user]_location() Christophe Leroy
2021-12-17 11:49 ` Christophe Leroy
2021-12-17 17:12 ` Helge Deller
2022-01-19 19:28 ` Christophe Leroy
2022-01-19 22:00 ` Kees Cook
2022-02-11 1:01 ` Kees Cook
2021-10-17 12:38 ` [PATCH v3 12/12] lkdtm: Add a test for function descriptors protection Christophe Leroy
2022-02-11 1:09 ` Kees Cook
2022-02-14 10:34 ` Christophe Leroy
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